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What does the 1st part of your text have to do with installing sophos? The 2nd line from the bottom is the one you use to install it and the last line clearly asks for your password. I see no problems here!? If it is about the 1st part: sudo itself needs a command behind it. sudo su will get you a root prompt.
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RinzwindMay 9 '12 at 6:49

2 Answers
2

When entering your password when using sudo, nothing is printed to the terminal. This is for security so people behind you aren't able to see the length of your password. So try again, enter your password (even though it looks like nothing is happening) then hit enter. It should run the install script.

It's not just so that people behind you don't see the length of the password, but also (1) so that subsequent users don't see it, if the screen isn't cleared, and (2) so that if you log the text printed to the console (for example, with script), the length doesn't appear in the log.
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Eliah KaganJun 18 '12 at 23:51